Medical image diagnosis apparatus and medical image processing method

ABSTRACT

A medical image diagnosis apparatus according to an embodiment obtains a first position of a predetermined part of an image taking target included in a medical robot system, a first direction of a rotation axis of the image taking target, and a first rotation angle of the image taking target, within a coordinate system of the medical image diagnosis apparatus. The medical image diagnosis apparatus derives information that brings the coordinate system of the medical image diagnosis apparatus and the coordinate system of the medical robot system into correspondence with each other, on the basis of the first position, the first direction, and the first rotation angle, as well as a second position of the predetermined part, a second direction of the rotation axis, and a second rotation angle of the image taking target, within a coordinate system of the medical robot system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2017-253484, filed on Dec. 28, 2017; theentire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a medical imagediagnosis apparatus and a medical image processing method.

BACKGROUND

There are peripheral devices (e.g., robots) that perform a manipulationsuch as a biopsy on an examined subject. For example, a peripheraldevice is configured to perform a biopsy by moving a puncture needlethrough a passage designated on a Computed Tomography (CT) image or aMulti Planar Reconstruction (MPR) image taken on an axialcross-sectional plane of the examined subject during an image takingprocess performed by a medical image diagnosis apparatus such as anX-ray CT apparatus.

To perform the manipulation accurately, it is necessary to align acoordinate system of the medical image diagnosis apparatus and acoordinate system of the peripheral device with each other.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of an imagetaking system according to a first embodiment;

FIG. 2 is a drawing for explaining an example of an operation performedby a robot according to the first embodiment;

FIG. 3 is a drawing illustrating examples of a robot arm and a holdingunit of the robot according to the first embodiment;

FIG. 4 is a drawing illustrating an example of an object according tothe first embodiment;

FIG. 5 is a drawing illustrating a specific example of the objectaccording to the first embodiment;

FIG. 6 is a flowchart illustrating a flow in an example of a coordinatesystem aligning process performed by an X-ray CT apparatus according tothe first embodiment;

FIG. 7 is a drawing for explaining a second modification example of thefirst embodiment;

FIG. 8 is another drawing for explaining the second modification exampleof the first embodiment;

FIG. 9 is yet another drawing for explaining the second modificationexample of the first embodiment;

FIG. 10 is a flowchart illustrating a flow in an example of a correctiondata deriving process performed by an X-ray CT apparatus according to asecond embodiment;

FIG. 11 is a drawing for explaining the correction data deriving processperformed by the X-ray CT apparatus according to the second embodiment;

FIG. 12 is a diagram illustrating an exemplary configuration of an imagetaking system according to a third embodiment;

FIG. 13 is a drawing for explaining an example of processes performed byan X-ray CT apparatus according to the third embodiment;

FIG. 14 is a drawing for explaining another example of the processesperformed by the X-ray CT apparatus according to the third embodiment;

FIG. 15 is a drawing for explaining yet another example of the processesperformed by the X-ray CT apparatus according to the third embodiment;and

FIG. 16 is a diagram illustrating an exemplary configuration of a robotmain body of a robot according to a fourth embodiment.

DETAILED DESCRIPTION

A medical image diagnosis apparatus according to an embodiment includesprocessing circuitry. The processing circuitry is configured to obtain afirst position of a predetermined part of an image taking target, afirst direction of a rotation axis of the image taking target, and afirst rotation angle of the image taking target, within a coordinatesystem of the medical image diagnosis apparatus, on the basis of imagedata acquired by imaging the image taking target that is one selectedfrom between a robot arm included in a medical robot system and holdinga medical tool and an object held by the robot arm. The processingcircuitry is configured to obtain a second position of the predeterminedpart, a second direction of the rotation axis, and a second rotationangle of the image taking target, within a coordinate system of themedical robot system. The processing circuitry is configured to deriveinformation that brings the coordinate system of the medical imagediagnosis apparatus and the coordinate system of the medical robotsystem into correspondence with each other, on the basis of the firstposition, the first direction, the first rotation angle, the secondposition, the second direction, and the second rotation angle.

Exemplary embodiments of a medical image diagnosis apparatus and amedical image processing method will be explained below, with referenceto the accompanying drawings. It is possible, in principle, to apply thedescription of each of the embodiments similarly to any otherembodiment.

First Embodiment

FIG. 1 is a diagram illustrating an exemplary configuration of an imagetaking system 100 according to a first embodiment. As illustrated inFIG. 1, the image taking system 100 according to the first embodimentincludes an X-ray CT apparatus 1, and a medical robot system 200. TheX-ray CT apparatus 1 is an example of the medical image diagnosisapparatus.

The X-ray CT apparatus 1 may be, for example, an Area Detector CT (ADCT)apparatus. The X-ray CT apparatus 1 includes a gantry 10, a couch 20,and a console 30. In the X-ray CT apparatus 1, a coordinate system 1 astructured with an X-axis, a Y-axis, and a Z-axis is defined. In otherwords, the coordinate system 1 a is an orthogonal coordinate system andis a coordinate system of the X-ray CT apparatus 1. The X-axisstructuring the coordinate system 1 a expresses a direction parallel tothe floor surface. The Y-axis expresses a direction perpendicular to thefloor surface. The Z-axis expresses either the direction of a rotationcenter axis of a rotating frame 15 (explained later) while the gantry 10is in a non-tilted state or the longitudinal direction of a couchtop 22of the couch 20.

The gantry 10 is a device configured to radiate X-rays onto an examinedsubject (hereinafter, “patient”) P and to acquire data related to X-raysthat have passed through the patient P. The gantry 10 includes an X-rayhigh-voltage device 11, an X-ray generating device 12, an X-ray detector13, a data acquiring circuit 14, the rotating frame 15, and a gantrycontrolling device 16. When the gantry controlling device 16 exercisestilting control thereon, the gantry 10 is configured to rotate on theX-axis (to roll), to rotate on the Y-axis (to pitch), and to rotate onthe Z-axis (to yaw).

The rotating frame 15 is an annular frame configured to support theX-ray generating device 12 and the X-ray detector 13 so as to opposeeach other while the patient P is interposed therebetween and to rotateat a high speed on a circular orbit centered on the patient P undercontrol exercised by the gantry controlling device 16.

The X-ray generating device 12 is a device configured to generate theX-rays and to radiate the generated X-rays onto the patient P. The X-raygenerating device 12 includes an X-ray tube 12 a, a wedge 12 b, and acollimator 12 c.

The X-ray tube 12 a is a vacuum tube configured to emit thermo electronsfrom a negative pole (which may be referred to as a filament) to apositive pole (a target), by receiving a supply of high voltage from theX-ray high-voltage device 11. The X-ray tube 12 a radiates an X-ray beamonto the patient P, as the rotating frame 15 rotates. In other words,the X-ray tube 12 a is configured to generate the X-rays by using thehigh voltage supplied thereto from the X-ray high-voltage device 11.

Further, the X-ray tube 12 a is configured to generate the X-ray beamthat spreads with a fan angle and a cone angle. For example, undercontrol of the X-ray high-voltage device 11, the X-ray tube 12 a iscapable of continuously emitting X-rays in the entire surrounding of thepatient P to realize a full reconstruction process and is capable ofcontinuously emitting X-rays in an emission range (180 degrees+the fanangle) that enables a half reconstruction to realize a halfreconstruction process. Further, under the control of the X-rayhigh-voltage device 11, the X-ray tube 12 a is capable of intermittentlyemitting X-rays (pulse X-rays) in positions (X-ray tube positions) setin advance. Further, the X-ray high-voltage device 11 is also capable ofmodulating intensities of the X-rays emitted from the X-ray tube 12 a.

The wedge 12 b is an X-ray filter configured to adjust the X-ray dose ofthe X-rays emitted from the X-ray tube 12 a. More specifically, thewedge 12 b is a filter configured to pass and attenuate the X-raysemitted from the X-ray tube 12 a, so that the X-rays radiated from theX-ray tube 12 a onto the patient P have a predetermined distribution.For example, the wedge 12 b is a filter obtained by processing aluminumso as to have a predetermined target angle and a predeterminedthickness. The wedge may be referred to as a wedge filter or a bow-tiefilter.

The collimator 12 c is configured by using a lead plate or the like andhas a slit in a part thereof. For example, by using the slit, thecollimator 12 c is configured to narrow down the radiation range of theX-rays of which the X-ray dose has been adjusted by the wedge 12 b,under the control of the X-ray high-voltage device 11.

Possible X-ray sources of the X-ray generating device 12 are not limitedto the X-ray tube 12 a. For example, in place of the X-ray tube 12 a,the X-ray generating device 12 may be structured with a focus coilconfigured to converge an electron beam generated by an electron gun, adeflection coil configured to electromagnetically deflect the electronbeam, and a target ring that covers a half of the surrounding of thepatient P and is configured to generate X-rays by having the deflectedelectron beam collide thereon.

The X-ray high-voltage device 11 is structured with: a high-voltagegenerating device that is configured by using an electric circuit suchas a transformer, a rectifier, and the like and that has a function ofgenerating the high voltage to be applied to the X-ray tube 12 a; and anX-ray controlling device configured to control the output voltage inaccordance with the X-rays to be radiated by the X-ray tube 12 a. Thehigh-voltage generating device may be of a transformer type or of aninverter type. For example, by adjusting the X-ray tube voltage and theX-ray tube current supplied to the X-ray tube 12 a, the X-rayhigh-voltage device 11 adjusts the dose of the X-rays radiated onto thepatient P. Further, the X-ray high-voltage device 11 operates asdescribed above, under control of processing circuitry 34 included inthe console 30.

The gantry controlling device 16 is structured with: processingcircuitry configured by using a processor or the like; and a drivingmechanism configured by using a motor, an actuator, and the like. Thegantry controlling device 16 has a function of controlling operations ofthe gantry 10 by receiving an input signal from either an inputinterface 31 (explained later) included in the console 30 or an inputinterface attached to the gantry 10. For example, the gantry controllingdevice 16 exercises control to cause the X-ray tube 12 a and the X-raydetector 13 to revolve on a circular orbit centered on the patient P, byrotating the rotating frame 15 upon receipt of the input signal. Asanother example, the gantry controlling device 16 exercises control totilt the gantry 10. The gantry controlling device 16 operates asdescribed above under the control of the processing circuitry 34included in the console 30.

The X-ray detector 13 is a two-dimensional array detector (an areadetector) configured to detect the X-rays that have passed through thepatient P. For example, the X-ray detector 13 has a structure in which aplurality of rows of X-ray detecting elements are arranged in the slicedirection, while each of the rows of X-ray detecting elements includes aplurality of X-ray detecting elements that are arranged in a channeldirection along an arc centered on a focal point of the X-ray tube 12 a.The X-ray detecting elements included in the X-ray detector 13 areconfigured to detect the X-rays that were radiated from the X-raygenerating device 12 and have passed through the patient P and are eachconfigured to output an electrical signal (a pulse) corresponding to anX-ray dose to the data acquiring circuit 14. In this situation, theelectrical signals output by the X-ray detector 13 may be referred to asdetection signals.

The data acquiring circuit 14 (a Data Acquisition System [DAS]) is acircuit configured to acquire the detection signals output from theX-ray detecting elements included in the X-ray detector 13, to generatedetection data from the acquired detection signals, and to output thegenerated detection data to the console 30.

In this situation, data obtained by applying one or more pre-processingprocesses such as a logarithmic conversion process, an offset correctingprocess, an inter-channel sensitivity correcting process, aninter-channel gain correcting process, a pile-up correcting process, abeam hardening correcting process, and/or the like to the detection datamay be referred to as raw data. Further, the detection data and the rawdata may collectively be referred to as projection data.

The couch 20 is a device on which the patient P to be scanned is placedand is configured to move the patient P placed thereon. The couch 20includes a couch driving device 21, the couchtop 22, a pedestal 23, anda base (a supporting frame) 24.

The couchtop 22 is a plate-like member on which the patient P is placed.The base 24 is configured to support the couchtop 22. The pedestal 23 isa casing configured to support the base 24 in such a manner that thebase 24 is able to move in directions perpendicular to the floorsurface. The couch driving device 21 is either a motor or an actuatorconfigured to move the patient P to the inside of the rotating frame 15by moving the couchtop 22 on which the patient P is placed, in alongitudinal direction of the couchtop 22 (the Z-axis direction in thecoordinate system 1 a). In addition, the couch driving device 21 is alsocapable of moving the couchtop 22 in the X-axis directions.

As for methods of moving the couchtop 22, it is acceptable to move onlythe couchtop 22. Alternatively, it is also acceptable to move the couch20 from the base 24 together therewith. Further, when the X-ray CTapparatus 1 is a standing CT apparatus, other methods are alsoacceptable in which the gantry 10 is moved in up-and-down directions(the directions perpendicular to the floor surface), in which a patientmoving mechanism corresponding to the couchtop 22 is moved, or in whichboth the gantry 10 and a patient moving mechanism are moved.

For example, the gantry 10 is configured to perform a conventional scanby which the patient P is scanned on a circular orbit by causing therotating frame 15 to rotate, while the position of the patient P isbeing fixed after the couchtop 22 is moved. Alternatively, the gantry 10may perform a helical scan by which the patient P is helically scannedby causing the rotating frame 15 to rotate while the couchtop 22 isbeing moved. In these situations, the relative position between thegantry 10 and the couchtop 22 may be changed by controlling the movingof the couchtop 22. Further, when the gantry 10 is self-propelled, therelative position between the gantry 10 and the couchtop 22 may bechanged by controlling the self-propelled movement of the gantry 10.Alternatively, the relative position between the gantry 10 and thecouchtop 22 may be changed by controlling the self-propelled movement ofthe gantry 10 and the moving of the couchtop 22. In other words, therelationship of the relative position between the patient P placed onthe couchtop 22 and the gantry 10 may be established by one or both ofthe self-propelled movement of the gantry 10 and the moving of thecouchtop 22.

The console 30 is a device configured to receive operations performed byan operator on the X-ray CT apparatus 1 and to reconstruct X-ray CTimage data by using the detection data output from the gantry 10. X-rayCT images may simply be referred to as CT images. As illustrated in FIG.1, the console 30 includes the input interface 31, a display device 32,a storage circuit 33, and the processing circuitry 34.

The input interface 31 is configured to receive various types of inputoperations from the operator, to convert the received input operationsinto electrical signals, and to output the electrical signals to theprocessing circuitry 34. For example, the input interface 31 receives,from the operator, an acquisition condition used for acquiring thedetection data, a reconstruction condition used for reconstructing CTimage data, an image processing condition used for generating apost-processing image from the CT image data, and the like. For example,the input interface 31 is realized with a mouse, a keyboard, atrackball, a switch, a button, a joystick, and/or the like.

The display device 32 is configured to display various types ofinformation. For example, the display device 32 is configured to outputa medical image (a CT image) generated by the processing circuitry 34, aGraphical User Interface (GUI) used for receiving various types ofoperations from the operator, and the like. For example, the displaydevice 32 may be a liquid crystal display device, a Cathode Ray Tube(CRT) display device, or the like.

The storage circuit 33 is realized by using, for example, asemiconductor memory element such as a Random Access Memory (RAM), aflash memory, or the like, a hard disk, an optical disk, or the like.For example, the storage circuit 33 is configured to store therein thedetection data, the raw data, the CT image data, and the like.

The processing circuitry 34 includes, for example, a system controllingfunction 34 a, a pre-processing function 34 b, a reconstructionprocessing function 34 c, an image processing function 34 d, a scancontrolling function 34 e, a display controlling function 34 f, a robotcontrolling function 34 g, a first obtaining function 34 h, a secondobtaining function 34 i, and a deriving function 34 j. In thissituation, for example, processing functions executed by the constituentelements of the processing circuitry 34 illustrated in FIG. 1, namely,the system controlling function 34 a, the pre-processing function 34 b,the reconstruction processing function 34 c, the image processingfunction 34 d, the scan controlling function 34 e, the displaycontrolling function 34 f, the robot controlling function 34 g, thefirst obtaining function 34 h, the second obtaining function 34 i, andthe deriving function 34 j, are recorded in the storage circuit 33 inthe form of computer-executable programs. For example, the processingcircuitry 34 is a processor and is configured to realize the functionscorresponding to the programs by reading and executing the programs fromthe storage circuit 33. In other words, the processing circuitry 34 thathas read the programs has the functions illustrated within theprocessing circuitry 34 in FIG. 1.

The system controlling function 34 a is configured to control varioustypes of functions of the processing circuitry 34 on the basis of theinput operations received from the operator via the input interface 31.

The pre-processing function 34 b is configured to generate the raw databy performing, on the detection data output from the data acquiringcircuit 14, one or more pre-processing processes such as a logarithmicconversion process, an offset correcting process, an inter-channelsensitivity correcting process, a beam hardening correcting process,and/or the like. The pre-processing function 34 b stores the generatedraw data into the storage circuit 33.

The reconstruction processing function 34 c is configured to reconstruct(generate) the CT image data by performing a reconstructing process thatuses a filter correction back projection method or a successiveapproximation reconstruction method on the raw data generated by thepre-processing function 34 b. For example, the reconstruction processingfunction 34 c reconstructs CT image data that is three-dimensional(three-dimensional CT image data, volume data) by obtaining the raw datastored in the storage circuit 33 and performing the reconstructingprocess on the obtained raw data. The reconstruction processing function34 c stores the reconstructed CT image data into the storage circuit 33.

To reconstruct the CT image data, the reconstruction processing function34 c is able to use a full-scan reconstruction scheme and a half-scanreconstruction scheme. For example, when using the full-scanreconstruction scheme, the reconstruction processing function 34 crequires raw data from the entire surrounding of the patientcorresponding to 360 degrees. In contrast, when using the half-scanreconstruction scheme, the reconstruction processing function 34 crequires raw data corresponding to 180 degrees+a fan angle.

The image processing function 34 d is configured to convert the CT imagedata reconstructed by the reconstruction processing function 34 c intoimage data of an MPR image or the like by using a publicly-known method,on the basis of an input operation received from the operator via theinput interface 31. The image processing function 34 d stores the imagedata resulting from the conversion into the storage circuit 33.

The scan controlling function 34 e is configured to control a CT scanperformed by the gantry 10. For example, the scan controlling function34 e controls execution of various types of scans performed by thegantry 10, by controlling operations of the X-ray high-voltage device11, the X-ray detector 13, the gantry controlling device 16, the dataacquiring circuit 14, and the couch driving device 21.

More specifically, the scan controlling function 34 e is configured tocontrol projection data acquiring processes in an image taking processto acquire a position determining image (a scanogram image, a scanogram)and a main image taking process (a scan) to acquire an image used for adiagnosis purpose. As a result of the scan controlling function 34 econtrolling the projection data acquiring processes, the X-ray CTapparatus 1 acquires the CT image data.

For example, the scan controlling function 34 e causes a conventionalscan or a helical scan to be executed. As a result, the X-ray CTapparatus 1 acquires the three-dimensional CT image data.

The display controlling function 34 f is configured to exercise controlso that the display device 32 displays any of various types of imagesrepresented by the various types of image data stored in the storagecircuit 33.

The robot controlling function 34 g is configured to control operationsof a robot 2 (explained later). For example, the robot controllingfunction 34 g causes the robot 2 to perform a manipulation such as abiopsy on the patient P. For example, the robot controlling function 34g causes the display device 32 to display a CT image or an MPR imagetaken on an axial cross-sectional plane of the patient P. After that,the robot controlling function 34 g receives a passage designated by theuser in the CT image or the MPR image. Further, the robot controllingfunction 34 g transmits position information of a plurality of pointsstructuring the received passage to the robot 2 and controls operationsof the robot 2 so as to perform the biopsy by moving a puncture needle40 (explained later). In other words, the robot controlling function 34g controls operations of the robot 2 so as to insert the puncture needle40 (explained later) into the patient P. In this situation, the robotcontrolling function 34 g transmits the position information of theplurality of points in the coordinate system 1 a, to the robot 2. Inthis manner, the robot controlling function 34 g controls the operationsof the robot 2 completely automatically.

In this situation, the robot controlling function 34 g may control theoperations of the robot 2 through a remote operation performed by theoperator. For example, as a result of the operator operating the inputinterface 31 or a lever (not illustrated), an instruction that causesthe robot 2 to operate is input to the processing circuitry 34. When theinstruction has been input to the processing circuitry 34, the robotcontrolling function 34 g controls operations of the robot 2 accordingto the instruction.

The first obtaining function 34 h, the second obtaining function 34 i,and the deriving function 34 j are configured to perform a coordinatesystem aligning process. Details of the first obtaining function 34 h,the second obtaining function 34 i, and the deriving function 34 j willbe explained later. The first obtaining function 34 h is an example of afirst obtaining unit and an obtaining unit. The second obtainingfunction 34 i is an example of a second obtaining unit. The derivingfunction 34 j is an example of a deriving unit.

The medical robot system 200 includes the robot 2. The robot 2 isinstalled with the X-ray CT apparatus 1. For example, the robot 2 may beattached to either the couchtop 22 or the gantry 10. Alternatively, therobot 2 may be mounted (fixed) onto the floor on which the couch 20 isplaced, in the vicinity of the couch 20.

The robot 2 is configured to perform manipulations such as a biopsy. Therobot 2 includes a robot main body 2 a, a robot arm 2 b, and a holdingunit 2 c. When a manipulation such as a biopsy is performed, the holdingunit 2 c holds the puncture needle 40. Accordingly, the robot arm 2 bholds the puncture needle 40 via the holding unit 2 c. The punctureneedle 40 is an example of the medical tool. In a tip end part of therobot arm 2 b, the holding unit 2 c is rotatably attached to the robotarm 2 b.

The robot main body 2 a is configured to support the robot arm 2 b whileallowing the robot arm 2 b to perform operations. The robot main body 2a includes processing circuitry 2 a_1 configured by using a processor orthe like and a driving mechanism 2 a_2 configured by using a motor andan actuator or the like and configured to cause the robot arm 2 b andthe holding unit 2 c to operate. For example, on the basis of theposition information of the plurality of points transmitted thereto fromthe robot controlling function 34 g, the processing circuitry 2 a_1 isconfigured to control operations of the robot arm 2 b and the holdingunit 2 c, so that the puncture needle 40 is inserted into the patient Pthrough the passage structured by the plurality of points. Morespecifically, the processing circuitry 2 a_1 controls the operations ofthe robot arm 2 b and the holding unit 2 c, by controlling the drivingmechanism 2 a_2.

The term “processor” used in the explanations above denotes, forexample, a Central Processing Unit (CPU), a Graphics Processing Unit(GPU), or a circuit such as an Application Specific Integrated Circuit(ASIC) or a programmable logic device (e.g., a Simple Programmable LogicDevice [SPLD], a Complex Programmable Logic Device [CPLD], or a FieldProgrammable Gate Array [FPGA]). The one or more processors realize thefunctions thereof by reading programs saved in a storage circuit andexecuting the read programs. In this situation, instead of saving theprograms in the storage circuit, it is also acceptable to directlyincorporate the programs in the circuits of the processors. In thatsituation, the processors realize the functions thereof by reading theprograms incorporated in the circuits thereof and executing the readprograms. Further, the one or more processors in the present embodimentsdo not each necessarily have to be structured as a single circuit. It isalso acceptable to structure one processor by combining together aplurality of independent circuits so as to realize the functionsthereof.

FIG. 2 is a drawing for explaining an example of an operation performedby the robot 2 according to the first embodiment. As illustrated in theexample in FIG. 2, the processing circuitry 2 a_1 controls operations ofthe robot arm 2 b so that the puncture needle 40 is inserted into apuncture target site 41 of the patient P placed on the couchtop 22. Theexample in FIG. 2 illustrates only the robot arm 2 b and the holdingunit 2 c among the constituent elements of the robot 2.

In this situation, in the medical robot system 200, a coordinate system2 d is defined. The processing circuitry 2 a_1 controls operations ofthe robot arm 2 b so that the puncture needle 40 is inserted into thepatient P through the designated passage, in the coordinate system 2 dof the medical robot system 200. The coordinate system 2 d is anorthogonal coordinate system structured with an X-axis, a Y-axis, and aZ-axis.

FIG. 3 is a drawing illustrating examples of the robot arm 2 b and theholding unit 2 c of the robot 2 according to the first embodiment. Therobot arm 2 b illustrated in the example in FIG. 3 performs operationsand changes postures thereof, under the control of the processingcircuitry 2 a_1.

Further, the holding unit 2 c illustrated in the example in FIG. 3 hasformed therein an insertion opening 2 c_1 through which the punctureneedle 40 can be inserted. When the puncture needle 40 has been insertedin the insertion opening 2 c_1, the puncture needle 40 is fixed to theholding unit 2 c.

By the driving mechanism 2 a_2, the holding unit 2 c is caused to rotatearound a rotation axis 2 e, either in a first rotation direction 2 f orin a second rotation direction 2 g, which is the opposite direction ofthe first rotation direction 2 f. Further, the holding unit 2 c isconfigured to stop the rotation thereof in such a position where therotation angle thereof becomes equal to a certain rotation angle withrespect to a reference rotation angle (e.g., 0 degrees). When theholding unit 2 c holding the puncture needle 40 rotates around therotation axis 2 e, it means that the puncture needle 40 also rotates.The rotation axis of the puncture needle 40 substantially coincides withthe rotation axis 2 e of the holding unit 2 c.

In this situation, the processing circuitry 2 a_1 learns the position(three-dimensional coordinates) of a predetermined part 2 h of the robotarm 2 b, the direction of the rotation axis 2 e, and the rotation angleof the holding unit 2 c, within the coordinate system 2 d using a pointO as the origin thereof, on the basis of an operation status of thedriving mechanism 2 a_2 and a detection signal from sensors attached tothe robot arm 2 b and to the holding unit 2 c. In this situation, thedirection of the rotation axis 2 e may be, for example, the direction inwhich the rotation axis 2 e extends.

The exemplary configuration of the image taking system 100 according tothe first embodiment has thus been explained. The X-ray CT apparatus 1according to the first embodiment structured as described above isconfigured to perform the coordinate system aligning process explainedbelow, so as to be able to easily and conveniently align the coordinatesystem 1 a of the X-ray CT apparatus 1 and the coordinate system 2 d ofthe medical robot system 200 with each other.

FIG. 4 is a drawing illustrating an example of an object 50 according tothe first embodiment. In the first embodiment, when the coordinatesystem aligning process is to be performed, the holding unit 2 c holdsthe object 50 as illustrated in the example in FIG. 4.

FIG. 5 is a drawing illustrating a specific example of the object 50according to the first embodiment. FIG. 5 is a top view of the object50. The object 50 illustrated in the example in FIG. 5 includes members50 a and 50 b. The members 50 a and 50 b are each a bar-like memberhaving a circular cylindrical shape. One end of the member 50 b islinked to one end of the member 50 a.

As illustrated in the example in FIG. 5, a marker 50 c is attached to apredetermined part 50 b_1 of the member 50 b that is positioned, in atop view, on a central axis 50 e of the member 50 a. Further, anothermarker 50 d is attached to a predetermined part 50 a_1 of the member 50a that is positioned, in a top view, on the central axis 50 e. In otherwords, the markers 50 c and 50 d are attached to two locations on thecentral axis 50 e. Accordingly, it is possible to identify the centralaxis 50 e in the coordinate system 1 a and to identify the direction ofthe central axis 50 e, on the basis of the position of the marker 50 cand the position of the marker 50 d within the coordinate system 1 a.The direction of the central axis 50 e may be, for example, thedirection in which the central axis 50 e extends.

Further, as illustrated in the example in FIG. 5, yet another marker 50f is attached to a predetermined part 50 b_2 of the member 50 b that ispositioned away from the marker 50 c by a predetermined distance alongthe direction of a central axis 50 g of the member 50 b. For example,the marker 50 f is attached in such a manner that, in a top view, anangle (a first angle) α formed by the central axis 50 e of the member 50a and the central axis 50 g of the member 50 b is substantially equal toa second angle. The second angle is an angle formed by a line segmentconnecting the marker 50 f to the marker 50 c and another line segmentconnecting the marker 50 c to the marker 50 d. In other words, thepredetermined part 50 b_2 is determined so that the angle (the secondangle) formed by a line segment connecting the predetermined part 50 b_1to the predetermined part 50 b_2 and another line segment connecting thepredetermined part 50 b_1 to the predetermined part 50 a_1 issubstantially equal to the angle α. In the example illustrated in FIG.5, the distance between the marker 50 c and the marker 50 d is differentfrom the distance between the marker 50 c and the marker 50 f. For thisreason, the positional relationship among the three markers 50 c, 50 d,and 50 f is an axially asymmetric positional relationship. The axiallyasymmetric positional relationship denotes, for example, a positionalrelationship in which, even when the positioning pattern of the markers50 c, 50 d, and 50 f is inverted by using a certain straight line as anaxis, the positioning pattern does not overlap with the invertedpositioning pattern. Further, although the angle α is 90 degrees in theexample illustrated in FIG. 5, the angle α may be an angle other than 90degrees. Further, it is sufficient when the object 50 is provided withmarkers in at least three locations. More specifically, to be able toidentify the direction of the central axis 50 e, it is sufficient whenthe object 50 is provided with markers in a plurality of locations ofwhich the quantity is at least three and which are not positioned onmutually the same straight line. In other words, the plurality ofmarkers are not positioned on mutually the same straight line.

Further, it is sufficient when the positional relationship among theplurality of markers provided in at least three locations is an axiallyasymmetric positional relationship. For example, in the exampleillustrated in FIG. 5, if the distance between the marker 50 c and themarker 50 d were equal to the distance between the marker 50 c and themarker 50 f, the positional relationship among the markers 50 c, 50 d,and 50 f would be an axially symmetric positional relationship that usesa straight line passing through the marker 50 c as the axis of symmetry.Accordingly, in that situation, the object 50 is newly provided with afourth marker so that the positional relationship among the four markersbecomes an axially asymmetric positional relationship.

The markers 50 c, 50 d, and 50 f may be formed by using, for example, amaterial of which the X-ray transmittance is either higher or lower thanthat of the materials used for structuring the robot arm 2 b and theholding unit 2 c.

On the basis of the position of the marker 50 c, the position of themarker 50 d, and the position of the marker 50 f within the coordinatesystem 1 a, it is possible to obtain the rotation angle, around thecentral axis 50 e, of the line segment connecting the marker 50 f to themarker 50 c, the rotation angle being observed when the object 50rotates while using the central axis 50 e as the rotation axis thereof.Accordingly, on the basis of the position of the marker 50 c, theposition of the marker 50 d, and the position of the marker 50 f withinthe coordinate system 1 a, it is possible to obtain the rotation angle,around the central axis 50 e, of the member 50 b that is observed withinthe coordinate system 1 a when the object 50 rotates while using thecentral axis 50 e as the rotation axis thereof. In other words, on thebasis of the position of the marker 50 c, the position of the marker 50d, and the position of the marker 50 f within the coordinate system 1 a,it is possible to obtain the rotation angle of the object 50 around thecentral axis 50 e within the coordinate system 1 a.

Further, the object 50 is held by the holding unit 2 c in such a mannerthat the central axis 50 e substantially coincides with the rotationaxis 2 e of the holding unit 2 c. Accordingly, when the holding unit 2 crotates around the rotation axis 2 e, the object 50 rotates while usingthe central axis 50 e as the rotation axis thereof. In the explanationsbelow, the rotation axis of the object 50 in that situation will bereferred to as a “rotation axis 50 h”.

Next, an example of the coordinate system aligning process will beexplained. FIG. 6 is a flowchart illustrating a flow in an example ofthe coordinate system aligning process performed by the X-ray CTapparatus 1 according to the first embodiment. The coordinate systemaligning process is performed, for example, when the input interface 31receives, from the user, an instruction to execute the coordinate systemaligning process and further inputs the instruction to execute thecoordinate system aligning process to the processing circuitry 34. Whenthe coordinate system aligning process is to be executed, the patient Pis not placed on the couch 20. Further, the coordinate system aligningprocess is an example of a process based on the medical image processingmethod.

As illustrated in FIG. 6, the robot controlling function 34 g controlsoperations of the robot 2 and keeps the object 50 stationary in an imagetaking range (a scan range) of the gantry 10 so that the object 50 heldby the holding unit 2 c of the robot 2 is positioned in the image takingrange (step S101).

After that, the scan controlling function 34 e causes a conventionalscan to be performed on the object 50 kept stationary in the imagetaking range, so that three-dimensional CT image data is acquired by theX-ray CT apparatus 1 (step S102). The acquired three-dimensional CTimage data is an example of the image data. The object 50 is an exampleof the image taking target.

Subsequently, on the basis of the acquired three-dimensional CT imagedata, the first obtaining function 34 h obtains the position of themarker 50 c, the position of the marker 50 d, and the position of themarker 50 f (the positions of the three markers) within the coordinatesystem 1 a (step S103). For example, at step S103, the first obtainingfunction 34 h identifies the positions of the marker 50 c, the marker 50d, and the marker 50 f within a coordinate system of thethree-dimensional CT image. After that, on the basis of a correspondencerelationship that is known between coordinates within the coordinatesystem of the three-dimensional CT image and coordinates within thecoordinate system 1 a, the first obtaining function 34 h obtains thepositions of the marker 50 c, the marker 50 d, and the marker 50 fwithin the coordinate system 1 a, on the basis of the positions of themarker 50 c, the marker 50 d, and the marker 50 f within the coordinatesystem of the three-dimensional CT image.

In this situation, the position of the marker 50 c and the position ofthe predetermined part 50 b_1 to which the marker 50 c is attached arepositioned close to each other. For this reason, the X-ray CT apparatus1 is able to treat the position of the marker 50 c as the position ofthe predetermined part 50 b_1 to which the marker 50 c is attached. Forthe same reason, the X-ray CT apparatus 1 is able to treat the positionof the marker 50 d as the position of the predetermined part 50 a_1 towhich the marker 50 d is attached. Similarly, the X-ray CT apparatus 1is able to treat the position of the marker 50 f as the position of thepredetermined part 50 b_2 to which the marker 50 f is attached. In thissituation, the position of the marker 50 c and the position of thepredetermined part 50 b_1 within the coordinate system 1 a are each anexample of the first position.

After that, on the basis of the position of the marker 50 c and theposition of the marker 50 d within the coordinate system 1 a, the firstobtaining function 34 h obtains the direction of the rotation axis 50 hof the object 50 within the coordinate system 1 a (step S104). Forexample, at step S104, on the basis of the position of the marker 50 cand the position of the marker 50 d within the coordinate system 1 a,the first obtaining function 34 h identifies the rotation axis 50 h ofthe object 50 within the coordinate system 1 a and further obtains thedirection of the rotation axis 50 h. The direction of the rotation axis50 h within the coordinate system 1 a is an example of the firstdirection.

Subsequently, on the basis of the position of the marker 50 c, theposition of the marker 50 d, and the position of the marker 50 f withinthe coordinate system 1 a, the first obtaining function 34 h obtains therotation angle of the object 50 within the coordinate system 1 a (stepS105). The rotation angle of the object 50 within the coordinate system1 a is an example of the first rotation angle.

After that, the second obtaining function 34 i obtains the position ofthe marker 50 c within the coordinate system 2 d, from the robot 2 (stepS106). In this situation, as explained above, the processing circuitry 2a_1 has learned the position (the three-dimensional coordinates) of thepredetermined part 2 h of the robot arm 2 b within the coordinate system2 d. In addition, the processing circuitry 2 a_1 has learned thepositional relationship between the predetermined part 2 h and themarker 50 c within the coordinate system 2 d. Accordingly, on the basisof the position of the predetermined part 2 h and the positionalrelationship between the predetermined part 2 h and the marker 50 c, theprocessing circuitry 2 a_1 is able to learn the position of the marker50 c within the coordinate system 2 d.

Accordingly, at step S106, the second obtaining function 34 i transmitsa request to the processing circuitry 2 a_1 of the robot 2 indicatingthat the position of the marker 50 c within the coordinate system 2 dshould be transmitted. When having received the request, the processingcircuitry 2 a_1 transmits the position of the marker 50 c within thecoordinate system 2 d to the processing circuitry 34. In this manner,the second obtaining function 34 i obtains the position of the marker 50c within the coordinate system 2 d, from the robot 2. In this situation,the position of the marker 50 c and the position of the predeterminedpart 50 b_1 within the coordinate system 2 d are each an example of thesecond position.

Subsequently, the second obtaining function 34 i obtains the directionof the rotation axis 50 h of the object 50 within the coordinate system2 d, from the robot 2 (step S107). In this situation, as explainedabove, the processing circuitry 2 a_1 has learned the direction of therotation axis 2 e within the coordinate system 2 d. Also, the directionof the rotation axis 2 e within the coordinate system 2 d substantiallycoincides with the direction of the rotation axis 50 h within thecoordinate system 2 d. Accordingly, the processing circuitry 2 a_1 isable to treat the direction of the rotation axis 2 e as the direction ofthe rotation axis 50 h.

Accordingly, at step S107, the second obtaining function 34 i transmitsa request to the processing circuitry 2 a_1 of the robot 2 indicatingthat the direction of the rotation axis 50 h within the coordinatesystem 2 d should be transmitted. When having received the request, theprocessing circuitry 2 a_1 transmits the direction of the rotation axis2 e within the coordinate system 2 d as the direction of the rotationaxis 50 h, to the processing circuitry 34. In this manner, the secondobtaining function 34 i has obtained the direction of the rotation axis50 h within the coordinate system 2 d, from the robot 2. The directionof the rotation axis 50 h within the coordinate system 2 d is an exampleof the second direction.

After that, the second obtaining function 34 i obtains the rotationangle of the object 50 within the coordinate system 2 d, from the robot2 (step S108). In this situation, as explained above, the processingcircuitry 2 a_1 has learned the rotation angle of the holding unit 2 cwithin the coordinate system 2 d. Also, the processing circuitry 2 a_1has learned a shift amount of the rotation angle of the object 50 withrespect to the rotation angle of the holding unit 2 c within thecoordinate system 2 d. Accordingly, on the basis of the rotation angleof the holding unit 2 c and the shift amount of the rotation angle ofthe object 50 with respect to the rotation angle of the holding unit 2c, the processing circuitry 2 a_1 is able to learn the rotation angle ofthe object 50 within the coordinate system 2 d.

Accordingly, at step S108, the second obtaining function 34 i transmitsa request to the processing circuitry 2 a_1 of the robot 2 indicatingthat the rotation angle of the object 50 within the coordinate system 2d should be transmitted. When having received the request, theprocessing circuitry 2 a_1 transmits the rotation angle of the object 50within the coordinate system 2 d to the processing circuitry 34. In thismanner, the second obtaining function 34 i has obtained the rotationangle of the object 50 within the coordinate system 2 d, from the robot2. The rotation angle of the object 50 within the coordinate system 2 dis an example of the second rotation angle.

After that, on the basis of the position of the marker 50 c, thedirection of the rotation axis 50 h of the object 50, and the rotationangle of the object 50 within the coordinate system 1 a, as well as theposition of the marker 50 c, the direction of the rotation axis 50 h ofthe object 50, and the rotation angle of the object 50 within thecoordinate system 2 d, the deriving function 34 j derives informationthat brings the coordinate system 1 a and the coordinate system 2 d intocorrespondence with each other (step S109).

For example, at step S109, the deriving function 34 j arranges thecoordinate system 1 a and the coordinate system 2 d to substantiallycoincide with each other, by translating and rotating the coordinatesystem 2 d.

In a specific example, the deriving function 34 j arranges thecoordinate system 1 a and the coordinate system 2 d to substantiallycoincide with each other, by arranging the position of the marker 50 cwithin the coordinate system 1 a and the position of the marker 50 cwithin the coordinate system 2 d to substantially coincide with eachother, arranging the direction of the rotation axis 50 h within thecoordinate system 1 a and the direction of the rotation axis 50 h withinthe coordinate system 2 d to substantially coincide with each other, andarranging the rotation angle of the object 50 within the coordinatesystem 1 a and the rotation angle of the object 50 within the coordinatesystem 2 d to substantially coincide with each other.

After that, at step S109, the deriving function 34 j derives atranslation amount and a rotation amount of the coordinate system 2 dthat were used for arranging the coordinate system 1 a and thecoordinate system 2 d to substantially coincide with each other, asinformation that brings the coordinate system 1 a and the coordinatesystem 2 d into correspondence with each other.

Subsequently, the deriving function 34 j notifies the robot 2 of theinformation that brings the coordinate system 1 a and the coordinatesystem 2 d into correspondence with each other (step S110). After that,the deriving function 34 j ends the coordinate system aligning process.

For example, when having received the information that brings thecoordinate system 1 a and the coordinate system 2 d into correspondencewith each other, the processing circuitry 2 a_1 included in the robot 2generates a transformation matrix used for transforming coordinateswithin the coordinate system 1 a into coordinates within the coordinatesystem 2 d, by using the received information. By using the generatedtransformation matrix, the processing circuitry 2 a_1 transforms theposition information within the coordinate system 1 a transmittedthereto from the robot controlling function 34 g, into positioninformation within the coordinate system 2 d. After that, the processingcircuitry 2 a_1 controls the robot arm 2 b and the holding unit 2 c byusing the position information within the coordinate system 2 dresulting from the transformation. In this manner, the processingcircuitry 2 a_1 brings the coordinate system 1 a and the coordinatesystem 2 d into correspondence with each other.

Alternatively, the processing circuitry 2 a_1 may correct the coordinatesystem 2 d so as to substantially coincide with the coordinate system 1a, by using the information that brings the coordinate system 1 a andthe coordinate system 2 d into correspondence with each other. In aspecific example, the processing circuitry 2 a_1 translates thecoordinate system 2 d by the translation amount indicated in thereceived information. Further, the processing circuitry 2 a_1 rotatesthe coordinate system 2 d by the rotation amount indicated in thereceived information. The deriving function 34 j may bring thecoordinate system 1 a and the coordinate system 2 d into correspondencewith each other in this manner.

Alternatively, the deriving function 34 j may generate thetransformation matrix described above, by using the information thatbrings the coordinate system 1 a and the coordinate system 2 d intocorrespondence with each other. After that, instead of transmitting theposition information within the coordinate system 1 a to the robot 2,the robot controlling function 34 g may transform the positioninformation within the coordinate system 1 a into position informationwithin the coordinate system 2 d by using the transformation matrix andmay further transmit the position information within the coordinatesystem 2 d resulting from the transformation, to the robot 2.

Step S101 is a step corresponding to the robot controlling function 34g. Step S101 is a step at which the robot controlling function 34 g isrealized as a result of the processing circuitry 34 reading andexecuting a predetermined program corresponding to the robot controllingfunction 34 g from the storage circuit 33. Further, step S102 is a stepcorresponding to the scan controlling function 34 e. Step S102 is a stepat which the scan controlling function 34 e is realized as a result ofthe processing circuitry 34 reading and executing a predeterminedprogram corresponding to the scan controlling function 34 e from thestorage circuit 33. Steps S103 through S105 are steps corresponding tothe first obtaining function 34 h. Steps S103 through S105 are steps atwhich the first obtaining function 34 h is realized as a result of theprocessing circuitry 34 reading and executing a predetermined programcorresponding to the first obtaining function 34 h from the storagecircuit 33. Steps S106 through S108 are steps corresponding to thesecond obtaining function 34 i. Steps S106 through S108 are steps atwhich the second obtaining function 34 i is realized as a result of theprocessing circuitry 34 reading and executing a predetermined programcorresponding to the second obtaining function 34 i from the storagecircuit 33. Steps S109 and S110 are steps corresponding to the derivingfunction 34 j. Steps S109 and S110 are steps at which the derivingfunction 34 j is realized as a result of the processing circuitry 34reading and executing a predetermined program corresponding to thederiving function 34 j from the storage circuit 33.

In the coordinate system aligning process described above, the firstobtaining function 34 h obtains the position of the predetermined part50 b_1 of the object 50, the direction of the rotation axis 50 h of theobject 50, and the rotation angle of the object 50 within the coordinatesystem 1 a of the X-ray CT apparatus 1, on the basis of thethree-dimensional CT image data acquired by imaging the object 50 heldby the robot 2. The second obtaining function 34 i obtains the positionof the predetermined part 50 b_1, the direction of the rotation axis 50h, and the rotation angle of the object 50 within the coordinate system2 d of the medical robot system 200, from the robot 2. The derivingfunction 34 j derives the information that brings the coordinate system1 a and the coordinate system 2 d into correspondence with each other,on the basis of the position, the direction, and the rotation angleobtained by the first obtaining function 34 h, as well as the position,the direction, the rotation angle obtained by the second obtainingfunction 34 i.

Further, in the coordinate system aligning process described above, thefirst obtaining function 34 h obtains the position of the predeterminedpart 50 b_1 of the object 50, the direction of the rotation axis 50 h ofthe object 50, and the rotation angle of the object 50 within thecoordinate system 1 a of the X-ray CT apparatus 1, on the basis of thethree-dimensional CT image data acquired by imaging the plurality ofmarkers 50 c, 50 d, and 50 f provided in the three locations of theobject 50.

In this manner, according to the first embodiment, it is possible toderive the information used for aligning the coordinate system 1 a ofthe X-ray CT apparatus 1 and the coordinate system 2 d of the medicalrobot system 200 with each other, without the need to have the userperform cumbersome operations. Consequently, according to the firstembodiment, it is possible to easily and conveniently align thecoordinate system 1 a of the X-ray CT apparatus 1 and the coordinatesystem 2 d of the medical robot system 200 with each other.

A First Modification Example of the First Embodiment

Next, a first modification example of the first embodiment will beexplained. In the first embodiment described above, the example isexplained in which the first obtaining function 34 h obtains theposition of the predetermined part 50 b_1 of the object 50, thedirection of the rotation axis 50 h of the object 50, and the rotationangle of the object 50 within the coordinate system 1 a of the X-ray CTapparatus 1, on the basis of the three-dimensional CT image dataacquired by imaging the object 50.

In contrast, in the first modification example of the first embodiment,the X-ray CT apparatus 1 includes a visible light camera. Further, inthe first modification example of the first embodiment, on the basis ofimage data acquired by imaging the object 50 while using the visiblelight camera, the first obtaining function 34 h obtains the position ofthe predetermined part 50 b_1 of the object 50, the direction of therotation axis 50 h of the object 50, and the rotation angle of theobject 50, within the coordinate system 1 a of the X-ray CT apparatus 1.

For example, on the basis of image data acquired by imaging markersprovided in at least three positions that are not positioned on mutuallythe same straight line while using the visible light camera, the firstobtaining function 34 h obtains the position of the predetermined part50 b_1 of the object 50, the direction of the rotation axis 50 h of theobject 50, and the rotation angle of the object 50, within thecoordinate system 1 a of the X-ray CT apparatus 1. For example, when astereo camera is used as the visible light camera, the first obtainingfunction 34 h obtains the position of the predetermined part 50 b_1 ofthe object 50, the direction of the rotation axis 50 h of the object 50,and the rotation angle of the object 50, within the coordinate system 1a of the X-ray CT apparatus 1, on the basis of two pieces of image dataacquired in one session of image taking process. A second modificationexample of the first embodiment

In the first embodiment, the example is explained in which, at step S102in the coordinate system aligning process, the X-ray CT apparatus 1acquires the three-dimensional CT image data as a result of the scancontrolling function 34 e causing the conventional scan to be performedon the object 50 kept stationary in the image taking range. When apredetermined condition is satisfied, however, at step S102, the X-rayCT apparatus 1 may acquire the three-dimensional CT image data as aresult of the scan controlling function 34 e causing a helical scan tobe performed on the object 50 kept stationary in the image taking range.

Thus, this modification example will be explained as a secondmodification example of the first embodiment. Some of the constituentelements that are the same as those in the first embodiment may bereferred to by using the same reference characters, and the explanationsthereof may be omitted. FIGS. 7 to 9 are drawings for explaining thesecond modification example of the first embodiment.

For example, as illustrated in the example in FIG. 7, when the gantry 10is moved during the helical scan while the robot 2 is fixed to a floorsurface 90, the relative positional relationship between the robot 2 andthe gantry 10 changes during the helical scan. For this reason, it ispossible to acquire volume data including the object 50 held by therobot 2, by performing the helical scan. Accordingly, when the gantry 10is moved during the helical scan while the robot 2 is placed on thefloor surface 90, the X-ray CT apparatus 1 may, at step S102, acquirethree-dimensional CT image data as a result of the scan controllingfunction 34 e causing the helical scan to be performed.

Further, as illustrated in the example in FIG. 8, also when the gantry10 is moved during a helical scan while the robot 2 is fixed to thecouchtop 22, the relative positional relationship between the robot 2and the gantry 10 changes during the helical scan. Accordingly, alsowhen the gantry 10 is moved during the helical scan while the robot 2 isfixed to the couchtop 22, the X-ray CT apparatus 1 may, at step S102,acquire three-dimensional CT image data as a result of the scancontrolling function 34 e causing the helical scan to be performed.

Further, as illustrated in the example in FIG. 9, also when the couchtop22 is moved during a helical scan, while the robot 2 is fixed to thecouchtop 22, the relative positional relationship between the robot 2and the gantry 10 changes during the helical scan. Accordingly, alsowhen the couchtop 22 is moved during the helical scan while the robot 2is fixed to the couchtop 22, the X-ray CT apparatus 1 may, at step S102,acquire three-dimensional CT image data as a result of the scancontrolling function 34 e causing the helical scan to be performed.

Second Embodiment

Next, an image taking system according to a second embodiment will beexplained. Some of the constituent elements that are the same as thosein the first embodiment may be referred to by using the same referencecharacters, and the explanations thereof may be omitted. In the secondembodiment, in addition to the various types of processes performed inthe first embodiment, the X-ray CT apparatus 1 is configured to performa correction data deriving process.

An example of the correction data deriving process performed by theX-ray CT apparatus 1 according to the second embodiment will beexplained. FIG. 10 is a flowchart illustrating a flow in an example ofthe correction data deriving process performed by the X-ray CT apparatus1 according to the second embodiment. The correction data derivingprocess is performed, for example, when the input interface 31 receives,from the user, an instruction to execute the correction data derivingprocess and further inputs the instruction to execute the correctiondata deriving process to the processing circuitry 34. When thecorrection data deriving process is to be executed, the patient P is notplaced on the couch 20. Further, the correction data deriving process isan example of a process based on the medical image processing method.

As illustrated in FIG. 10, the robot controlling function 34 g controlsoperations of the robot 2 so that the object 50 is kept stationarywithin an image taking range of the gantry 10 while maintaining apredetermined first posture, in such a manner that the object 50 held bythe holding unit 2 c of the robot 2 is positioned within the imagetaking range and is in the first posture (step S201).

FIG. 11 is a drawing for explaining the correction data deriving processperformed by the X-ray CT apparatus 1 according to the secondembodiment. For example, at step S201, the robot controlling function 34g controls operations of the robot 2 so that the object 50 is keptstationary within the image taking range while maintaining a firstposture 60, as illustrated in the example in FIG. 11.

Subsequently, the X-ray CT apparatus 1 acquires three-dimensional CTimage data, as a result of the scan controlling function 34 e causing aconventional scan to be performed on the object 50 that is keptstationary within the image taking range while maintaining the firstposture 60 (step S202).

After that, the first obtaining function 34 h obtains the position ofthe marker 50 c within the coordinate system 1 a, on the basis of thethree-dimensional CT image data acquired at step S202 (step S203).

Subsequently, from the robot 2, the second obtaining function 34 iobtains the position of the marker 50 c of the object 50 that is keptstationary within the image taking range while maintaining the firstposture 60, the position being expressed within the coordinate system 2d (step S204).

After that, the robot controlling function 34 g controls operations ofthe robot 2 so that the object 50 is kept stationary within the imagetaking range of the gantry 10 while maintaining a predetermined secondposture different from the first posture, so that the object 50 ispositioned within the image taking range and is in the second posture(step S205).

For example, at step S205, the robot controlling function 34 g controlsoperations of the robot 2 so that the object 50 is kept stationary inthe image taking range while maintaining a second posture 61, asillustrated in the example in FIG. 11.

Subsequently, the X-ray CT apparatus 1 acquires three-dimensional CTimage data, as a result of the scan controlling function 34 e causing aconventional scan to be performed on the object 50 that is keptstationary within the image taking range while maintaining the secondposture 61 (step S206).

After that, on the basis of the three-dimensional CT image data acquiredat step S206, the first obtaining function 34 h obtains the position ofthe marker 50 c within the coordinate system 1 a (step S207).

Subsequently, from the robot 2, the second obtaining function 34 iobtains the position of the marker 50 c of the object 50 that is keptstationary within the image taking range while maintaining the secondposture 61, the position being expressed within the coordinate system 2d (step S208).

After that, the first obtaining function 34 h obtains a moving amount ofthe marker 50 c within the coordinate system 1 a that is observed thenthe posture of the robot 2 is changed from the first posture 60 into thesecond posture 61 (step S209). For example, at step S209, the firstobtaining function 34 h calculates the distance between the position ofthe marker 50 c within the coordinate system 1 a obtained at step S203and the position of the marker 50 c within the coordinate system 1 aobtained at step S207 and thus obtains the calculated distance as themoving amount of the marker 50 c within the coordinate system 1 a.

In this situation, the X-ray CT apparatus 1 is able to treat the movingamount of the marker 50 c within the coordinate system 1 a as the movingamount of the predetermined part 50 b_1 within the coordinate system 1a. The moving amount of the marker 50 c within the coordinate system 1 aand the moving amount of the predetermined part 50 b_1 within thecoordinate system 1 a are each an example of the first moving amount.

After that, the second obtaining function 34 i obtains a moving amountof the marker 50 c within the coordinate system 2 d that is observedwhen the posture of the robot 2 is changed from the first posture 60into the second posture (step S210). For example, at step S210, thesecond obtaining function 34 i calculates the distance between theposition of the marker 50 c within the coordinate system 2 d obtained atstep S204 and the position of the marker 50 c within the coordinatesystem 2 d obtained at step S208 and thus obtains the calculateddistance as the moving amount of the marker 50 c within the coordinatesystem 2 d.

In this situation, the X-ray CT apparatus 1 is able to treat the movingamount of the marker 50 c within the coordinate system 2 d as the movingamount of the predetermined part 50 b_1 within the coordinate system 2d. The moving amount of the marker 50 c within the coordinate system 2 dand the moving amount of the predetermined part 50 b_1 within thecoordinate system 2 d are each an example of the second moving amount.

Subsequently, the deriving function 34 j derives correction data usedfor correcting an error between the moving amount of the robot 2 withinthe coordinate system 1 a and the moving amount of the robot 2 withinthe coordinate system 2 d (step S211). For example, the derivingfunction 34 j derives the correction data on the basis of the movingamount of the marker 50 c within the coordinate system 1 a obtained atstep S209 and the moving amount of the marker 50 c within the coordinatesystem 2 d obtained at step S210.

For example, an example will be explained in which, at step S205explained above, the robot controlling function 34 g has arranged theposture of the robot 2 to be the second posture, by transmitting aninstruction to the processing circuitry 2 a_1 included in the robot 2 soas to indicate that the marker 50 c should be moved 20 mm in thepositive direction on the X-axis.

On the basis of an operation status of the driving mechanism 2 a_2 anddetection signals from the sensors attached to the robot arm 2 b and tothe holding unit 2 c, the processing circuitry 2 a_1 has learned theposition of the marker 50 c within the coordinate system 2 d and themoving amount thereof in the positive direction on the X-axis. Further,upon determining that the marker 50 c has moved 20.0 mm in the positivedirection on the X-axis within the coordinate system 2 d, the processingcircuitry 2 a_1 makes the robot 2 stationary. Accordingly, the movingamount of the marker 50 c within the coordinate system 2 d obtained atstep S210 is 20.0 mm.

In this situation, let us discuss a situation in which the moving amountof the marker 50 c within the coordinate system 1 a obtained at stepS209 is different from 20.0 mm and is 20.3 mm, for example. As anexample, when the level of precision of either one of the sensorsattached to the robot arm 2 b and the holding unit 2 c is not excellent,or the like, the marker 50 c may move by a moving amount different from20.0 mm, which is the designated moving amount. In that situation, themoving amount of the marker 50 c within the coordinate system 1 aobtained at step S209 is different from 20.0 mm.

To cope with this situation, at step S211, the deriving function 34 jderives correction data calculated as, for example “the moving amount ofthe marker 50 c within the coordinate system 2 d obtained at stepS210/the moving amount of the marker 50 c within the coordinate system 1a obtained at step S209”. For example, the deriving function 34 jcalculates the correction data as “20.0/20.3” where the symbol “/” is adivision operator. The correction data can be used, for example, whenthe robot controlling function 34 g moves the robot arm 2 b or theholding unit 2 c of the robot 2.

For instance, an example will be explained in which the input interface31 has received, from the user, an instruction to move a predeterminedpart of the robot arm 2 b by a predetermined distance D (mm) in thepositive direction on the X-axis. In that situation, the robotcontrolling function 34 g transmits an instruction indicating that thepredetermined part of the robot arm 2 b should be moved by “D×(20/20.3)”mm in the positive direction on the X-axis, to the processing circuitry2 a_1 included in the robot 2. Accordingly, the moving amount by whichthe predetermined part of the robot arm 2 b moves becomes closer to thepredetermined distance D designated by the user. Consequently, the X-rayCT apparatus 1 according to the second embodiment is further capable ofinhibiting degradation in the level of precision of the moving controlexercised on the robot 2.

Further, the X-ray CT apparatus 1 according to the second embodiment iscapable of easily and conveniently aligning the coordinate system 1 aand the coordinate system 2 d with each other, similarly to the X-ray CTapparatus 1 according to the first embodiment.

Third Embodiment

Next, an image taking system according to a third embodiment will beexplained. Some of the constituent elements that are the same as thosein the first and/or the second embodiment may be referred to by usingthe same reference characters, and the explanations thereof may beomitted.

FIG. 12 is a diagram illustrating an exemplary configuration of an imagetaking system 100 a according to the third embodiment. As illustrated inFIG. 12, the image taking system 100 a includes an X-ray CT apparatus 1b and the robot 2.

The processing circuitry 34 of the X-ray CT apparatus 1 b according tothe third embodiment further includes a notifying function 34 k, inaddition to the configuration of the processing circuitry 34 of theX-ray CT apparatus 1 according to the first or the second embodiment. Inother words, in the X-ray CT apparatus 1 b according to the thirdembodiment, processes by the notifying function 34 k are performed, inaddition to the processes performed in the X-ray CT apparatus 1according to the first or the second embodiment.

FIGS. 13 to 15 are drawings for explaining examples of the processesperformed by the X-ray CT apparatus 1 b according to the thirdembodiment. In the following sections, examples in which the robot 2performs a manipulation such as a biopsy will be explained.

For example, as illustrated in the example in FIG. 13, when the couchtop22 on which the patient P is placed is moved during the manipulationwhile the robot 2 is fixed to the floor surface 90, the relativepositional relationship between the robot 2 and the couchtop 22 changes.When the relative positional relationship between the robot 2 and thecouchtop 22 changes, the relative positional relationship between therobot 2 and the patient P also changes. Accordingly, when the relativepositional relationship between the couchtop 22 and the robot 2 ischanged due to the moving of the couchtop 22, the notifying function 34k calculates a moving amount of the couchtop 22 that is moved at thetime of the change in the positional relationship. Further, thenotifying function 34 k notifies the processing circuitry 2 a_1 includedin the robot 2 of the calculated moving amount of the couchtop 22. Themoving amount of the couchtop 22 is an example of the change amount inthe positional relationship.

When being notified of the moving amount of the couchtop 22, theprocessing circuitry 2 a_1 derives the position of the couchtop 22observed after the relative positional relationship is changed, byadding the moving amount of the couchtop 22 indicated in thenotification to the position of the couchtop 22 observed before therelative positional relationship is changed, within the coordinatesystem 2 d. Accordingly, the processing circuitry 2 a_1 is able to learnthe position of the couchtop 22 observed after the relative positionalrelationship is changed. As a result, the robot 2 is able to learn theposition of the patient P placed on the couchtop 22 observed after therelative positional relationship is changed.

In the example in FIG. 13, for example, when the distance between thecouchtop 22 and the robot 2 is changed within the coordinate system 2 don at least one of the plurality of axes (i.e., the X-, the Y-, and theZ-axes) structuring the coordinate system 2 d, the notifying function 34k performs the following process: The notifying function 34 k, forexample, provides a notification about a change amount in the distancebetween the couchtop 22 and the robot 2 as the moving amount of thecouchtop 22.

Further, as illustrated in the example in FIG. 14, instead of thecouchtop 22 on which the patient P is placed, when the gantry 10 ismoved during the manipulation while the robot 2 is fixed to the gantry10, the relative positional relationship between the robot 2 and thecouchtop 22 changes. As a result, the relative positional relationshipbetween the robot 2 and the patient P also changes. Accordingly, whenthe relative positional relationship between the couchtop 22 and therobot 2 is changed due to the moving of the gantry 10 to which the robot2 is fixed, the notifying function 34 k calculates a moving amount ofthe gantry 10 that is moved at the time of the change in the positionalrelationship. Further, the notifying function 34 k notifies theprocessing circuitry 2 a_1 included in the robot 2 of the calculatedmoving amount of the gantry 10. The moving amount of the gantry 10 is anexample of the change amount in the positional relationship.

When being notified of the moving amount of the gantry 10, theprocessing circuitry 2 a_1 derives the position of the couchtop 22observed after the relative positional relationship is changed, on thebasis of the position of the couchtop 22 observed before the relativepositional relationship is changed and the moving amount of the gantry10 indicated in the notification, within the coordinate system 2 d.Accordingly, the processing circuitry 2 a_1 is able to learn theposition of the couchtop 22 observed after the relative positionalrelationship is changed. As a result, the robot 2 is able to learn theposition of the patient P placed on the couchtop 22 observed after therelative positional relationship is changed.

In the example illustrated in FIG. 14 where the gantry 10 is moved, forexample, when the distance between the couchtop 22 and the robot 2 ischanged within the coordinate system 2 d on at least one of theplurality of axes structuring the coordinate system 2 d (situation 1),the notifying function 34 k performs the following process: Thenotifying function 34 k, for example, provides a notification about achange amount in the distance between the couchtop 22 and the robot 2 asthe moving amount of the gantry 10.

Further, in the example illustrated in FIG. 14 where the gantry 10 ismoved, for example, when the rotation angle of the robot 2 is changedwithin the coordinate system 2 d with respect to the rotation angle ofthe couchtop 22 around at least one of the plurality of axes structuringthe coordinate system 2 d (situation 2), the notifying function 34 kperforms the following process: The notifying function 34 k, forexample, provides a notification about a change amount in the rotationangle of the robot 2 with respect to the rotation angle of the couchtop22, as the moving amount of the gantry 10.

In other words, when at least one selected from between situation 1 andsituation 2 occurs, the notifying function 34 k notifies the robot 2 ofat least one selected from between the change amount in the distance andthe change amount in the rotation angle.

Further, as illustrated in the example in FIG. 15, when the couchtop 22on which the patient P is placed is moved during the manipulation whilethe robot 2 is fixed to the gantry 10, the relative positionalrelationship between the robot 2 and the couchtop 22 changes. As aresult, the relative positional relationship between the robot 2 and thepatient P also changes. Accordingly, when the relative positionalrelationship between the couchtop 22 and the robot 2 is changed due tothe moving of the couchtop 22, the notifying function 34 k calculates amoving amount of the couchtop 22 that is moved at the time of the changein the positional relationship. Further, the notifying function 34 knotifies the processing circuitry 2 a_1 included in the robot 2 of thecalculated moving amount of the couchtop 22.

In the example illustrated in FIG. 15 where the couchtop 22 is moved,for example, when the distance between the couchtop 22 and the robot 2is changed within the coordinate system 2 d on at least one of theplurality of axes structuring the coordinate system 2 d (situation 3),the notifying function 34 k performs the following process: Thenotifying function 34 k, for example, provides a notification about achange amount in the distance between the couchtop 22 and the robot 2 asthe moving amount of the couchtop 22.

Further, in the example illustrated in FIG. 15 where the couchtop 22 ismoved, for example, when the rotation angle of the robot 2 is changedwith respect to the rotation angle of the couchtop 22 within thecoordinate system 2 d, on at least one of the plurality of axesstructuring the coordinate system 2 d (situation 4), the notifyingfunction 34 k performs the following process: The notifying function 34k, for example, provides a notification about a change amount in therotation angle of the robot 2 with respect to the rotation angle of thecouchtop 22, as the moving amount of the couchtop 22.

In other words, when at least one selected from between situation 3 andsituation 4 occurs, the notifying function 34 k notifies the robot 2 ofat least one selected from between the change amount in the distance andthe change amount in the rotation angle.

As explained above, when the relative positional relationship betweenthe robot 2 and the patient P is changed, the X-ray CT apparatus 1 baccording to the third embodiment is configured to notify the robot 2 ofone selected from between the moving amount of the gantry 10 and themoving amount of the couchtop 22. Consequently, even when the relativepositional relationship between the robot 2 and the patient P ischanged, the X-ray CT apparatus 1 b according to the third embodiment iscapable of enabling the robot 2 to learn the position of the patient Pobserved after the relative positional relationship is changed.

The X-ray CT apparatus 1 according to the third embodiment is capable ofeasily and conveniently aligning the coordinate system 1 a and thecoordinate system 2 d with each other, similarly to the X-ray CTapparatus 1 according to the first embodiment and the X-ray CT apparatus1 according to the second embodiment.

Fourth Embodiment

The processing circuitry 2 a_1 of the robot 2 may include functions thatare the same as the first obtaining function 34 h, the second obtainingfunction 34 i, and the deriving function 34 j described above. Thus,this embodiment will be explained as a fourth embodiment. Some of theconstituent elements that are the same as those in the first embodiment,the second embodiment, and/or the third embodiment may be referred to byusing the same reference characters, and the explanations thereof may beomitted.

An image taking system according to the fourth embodiment has the sameconfiguration as that of the image taking system 100 according to thefirst or the second embodiment or that of the image taking system 100 aaccording to the third embodiment. It should be noted, however, that theprocessing circuitry 34 does not necessarily have to include the firstobtaining function 34 h, the second obtaining function 34 i, and thederiving function 34 j.

FIG. 16 is a drawing illustrating an exemplary configuration of a robotmain body 2 a of the robot 2 according to the fourth embodiment. Theprocessing circuitry 2 a_1 of the robot main body 2 a according to thefourth embodiment includes an obtaining function 70 and a derivingfunction 71.

The processing circuitry 2 a_1 according to the fourth embodiment isconfigured to further execute processes performed by the obtainingfunction 70 and processes performed by the deriving function 71, inaddition to the processes executed by the processing circuitry 2 a_1according to the first, the second, or the third embodiment.

In the fourth embodiment, of the coordinate system aligning processillustrated in FIG. 6, the robot controlling function 34 g performs theprocess at step S101, whereas the scan controlling function 34 eperforms the process at step S102. Further, the scan controllingfunction 34 e transmits the three-dimensional CT image data acquired asa result of the process at step S102, to the processing circuitry 2 a_1.

Subsequently, by using the three-dimensional CT image data transmittedat step S102, the obtaining function 70 performs the same processes asthose at steps S103 through S105 explained above. The obtaining function70 is an example of an obtaining unit.

After that, by performing the same process as the process at step S109explained above, the deriving function 71 derives information thatbrings the coordinate system 1 a and the coordinate system 2 d intocorrespondence with each other. Subsequently, the deriving function 71notifies the X-ray CT apparatus 1 of the information that brings thecoordinate system 1 a and the coordinate system 2 d into correspondencewith each other, so that the X-ray CT apparatus 1 arranges thecoordinate system 1 a to substantially coincide with the coordinatesystem 2 d. The deriving function 71 is an example of a deriving unit.

In other words, the obtaining function 70 according to the fourthembodiment is configured to obtain the position of the predeterminedpart 50 b_1 of the object 50, the direction of the rotation axis 50 h ofthe object 50, and the rotation angle of the object 50 within thecoordinate system 1 a, on the basis of the three-dimensional CT imagedata acquired by imaging the object 50 held by the robot 2. Further, thederiving function 71 according to the fourth embodiment derives theinformation that brings the coordinate system 1 a and the coordinatesystem 2 d into correspondence with each other, on the basis of theposition, the direction, the rotation angle obtained by the obtainingfunction 70, as well as the position of the predetermined part 50 b_1,the direction of the rotation axis 50 h, and the rotation angle of theobject 50 within the coordinate system 2 d.

The X-ray CT apparatus according to the fourth embodiment is capable ofeasily and conveniently aligning the coordinate system 1 a and thecoordinate system 2 d with each other, similarly to the X-ray CTapparatus 1 according to the first embodiment and the like.

In the image taking system 100 or the image taking system 100 a, anotherarrangement is acceptable in which, while a workstation is connected tothe X-ray CT apparatus 1, the workstation is configured to have the samefunctions as those of the first obtaining function 34 h, the secondobtaining function 34 i, and the deriving function 34 j described above.Further, it is also acceptable to configure the workstation to have thesame functions as the obtaining function 70 and the deriving function 71described above.

Further, in the embodiments described above, the robot 2 is arranged tohold the object 50, when the coordinate system aligning process and thecorrection data deriving process are performed. Further, in theembodiments described above, the coordinate system aligning process andthe correction data deriving process are performed by using thethree-dimensional CT image data acquired by imaging the object 50.

However, another arrangement is also acceptable in which the robot 2 hasformed therewith a member having the same shape as that of the object50, as a member constituting a part of the robot 2. For example, therobot arm 2 b may have formed therewith a member having the same shapeas that of the object 50. Further, in the embodiments described above,the markers 50 c, 50 d, and 50 f are attached to the predetermined parts50 a_1, 50 b_1, and 50 b_2 of the object 50, respectively. However, aplurality of markers may similarly be pasted onto a plurality ofpredetermined parts (parts in at least three locations) of the robot 2.For example, the plurality of markers may be pasted onto a plurality ofpredetermined parts of the robot arm 2 b. In this situation, asexplained in the embodiments above, the plurality of markers are notpositioned on mutually the same straight line. Further, it is sufficientwhen the positional relationship among the plurality of markers providedin at least three locations is an axially asymmetric positionalrelationship. Further, the first obtaining function 34 h, the secondobtaining function 34 i, and the deriving function 34 j may perform thecoordinate system aligning process and the correction data derivingprocess by using three-dimensional CT image data acquired by imaging therobot 2 described above, in place of the object 50.

When the robot arm 2 b has formed therewith the member that has the sameshape as that of the object 50, or when the plurality of markers arepasted on the robot arm 2 b, the first obtaining function 34 h, thesecond obtaining function 34 i, and the deriving function 34 j mayperform processes by using the data described below. For example, thefirst obtaining function 34 h, the second obtaining function 34 i, andthe deriving function 34 j may perform the coordinate system aligningprocess and the correction data deriving process by usingthree-dimensional CT image data acquired by imaging the robot arm 2 b.The robot arm 2 b is an example of the image taking target.

Similarly, the obtaining function 70 and the deriving function 71 mayperform the coordinate system aligning process and the correction dataderiving process by using three-dimensional CT image data acquired byimaging the robot 2 described above. The robot 2 is an example of theperipheral device and is an example of the image taking target.

When the robot arm 2 b has formed therewith the member that has the sameshape as that of the object 50, or when the plurality of markers arepasted on the robot arm 2 b, the obtaining function 70 and the derivingfunction 71 may perform processes by using the data described below. Forexample, the obtaining function 70 and the deriving function 71 mayperform the coordinate system aligning process and the correction dataderiving process by using three-dimensional CT image data acquired byimaging the robot arm 2 b.

According to at least one aspect of the embodiments described above, itis possible to easily and conveniently align the coordinate system 1 aand the coordinate system 2 d with each other.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A medical image diagnosis apparatus comprisingprocessing circuitry configured: to obtain a first position of apredetermined part of an image taking target, a first direction of arotation axis of the image taking target, and a first rotation angle ofthe image taking target, within a coordinate system of the medical imagediagnosis apparatus, on a basis of image data acquired by imaging theimage taking target that is one selected from between a robot armincluded in a medical robot system and holding a medical tool and anobject held by the robot arm; to obtain a second position of thepredetermined part, a second direction of the rotation axis, and asecond rotation angle of the image taking target, within a coordinatesystem of the medical robot system; and to derive information thatbrings the coordinate system of the medical image diagnosis apparatusand the coordinate system of the medical robot system intocorrespondence with each other, on a basis of the first position, thefirst direction, the first rotation angle, the second position, thesecond direction, and the second rotation angle.
 2. The medical imagediagnosis apparatus according to claim 1, wherein the processingcircuitry obtains the first position, the first direction, and the firstrotation angle, on the basis of the image data acquired by imaging aplurality of markers that are provided in at least three locations ofthe image taking target and that are not positioned on a mutually samestraight line.
 3. The medical image diagnosis apparatus according toclaim 2, wherein a positional relationship among the plurality ofmarkers is an axially asymmetric positional relationship.
 4. The medicalimage diagnosis apparatus according to claim 1, wherein the processingcircuitry obtains the first position, the first direction, and the firstrotation angle on a basis of three-dimensional CT image data acquired byimaging the image taking target.
 5. The medical image diagnosisapparatus according to claim 1, wherein the processing circuitry furtherobtains a first moving amount of the predetermined part within thecoordinate system of the medical image diagnosis apparatus, the firstmoving amount being observed when a posture of the robot arm is changedfrom a first posture to a second posture that is different from thefirst posture, on a basis of two pieces of image data acquired byimaging the image taking target when the robot arm is in the firstposture and when the robot arm is in the second posture, the processingcircuitry further obtains a second moving amount of the predeterminedpart within the coordinate system of the medical robot system, thesecond moving amount being observed when the posture of the robot arm ischanged from the first posture to the second posture, and on a basis ofthe first moving amount and the second moving amount, the processingcircuitry further derives correction data used for correcting an errorbetween a moving amount of the robot arm within the coordinate system ofthe medical image diagnosis apparatus and a moving amount of the robotarm within the coordinate system of the medical robot system.
 6. Themedical image diagnosis apparatus according to claim 1, furthercomprising a couchtop on which a patient may be placed, wherein when arelative positional relationship between the couchtop and the medicalrobot system is changed, the processing circuitry notifies the medicalrobot system of a change amount in the positional relationship.
 7. Themedical image diagnosis apparatus according to claim 6, wherein, when atleast one of the following two is changed within the coordinate systemof the medical image diagnosis apparatus due to either moving of thecouchtop or moving of a gantry to which the robot arm is fixed: (i) adistance between the couchtop and the robot arm on at least one of aplurality of axes structuring the coordinate system of the medical imagediagnosis apparatus; and (ii) a rotation angle of the robot arm withrespect to a rotation angle of the couchtop around at least one of theplurality of axes, the processing circuitry notifies the medical robotsystem of at least one selected from between a change amount in thedistance between the couchtop and the robot arm and a change amount inthe rotation angle of the robot arm with respect to the rotation angleof the couchtop.
 8. The medical image diagnosis apparatus according toclaim 1, wherein the processing circuitry derives the information byarranging the first position and the second position to coincide witheach other, arranging the first direction and the second direction tocoincide with each other, and arranging the first rotation angle and thesecond rotation to coincide with each other.
 9. A medical imageprocessing method comprising: obtaining a first position of apredetermined part of an image taking target, a first direction of arotation axis of the image taking target, and a first rotation angle ofthe image taking target, within a coordinate system of a medical imagediagnosis apparatus, on a basis of image data acquired by imaging theimage taking target that is one selected from between a robot armincluded in a medical robot system and holding a medical tool and anobject held by the robot arm; obtaining a second position of thepredetermined part, a second direction of the rotation axis, and asecond rotation angle of the image taking target, within a coordinatesystem of the medical robot system; and deriving information that bringsthe coordinate system of the medical image diagnosis apparatus and thecoordinate system of the medical robot system into correspondence witheach other, on a basis of the first position, the first direction, thefirst rotation angle, the second position, the second direction, and thesecond rotation angle.
 10. The medical image processing method accordingto claim 9, comprising obtaining the first position, the firstdirection, and the first rotation angle, on the basis of the image dataacquired by imaging a plurality of markers that are provided in at leastthree locations of the image taking target and that are not positionedon a mutually same straight line.
 11. The medical image processingmethod according to claim 10, wherein a positional relationship amongthe plurality of markers is an axially asymmetric positionalrelationship.
 12. The medical image processing method according to claim9, comprising obtaining the first position, the first direction, and thefirst rotation angle on a basis of three-dimensional CT image dataacquired by imaging the image taking target.
 13. The medical imageprocessing method according to claim 9, comprising: obtaining a firstmoving amount of the predetermined part within the coordinate system ofthe medical image diagnosis apparatus, the first moving amount beingobserved when a posture of the robot aim is changed from a first postureto a second posture that is different from the first posture, on a basisof two pieces of image data acquired by imaging the image taking targetwhen the robot arm is in the first posture and when the robot ai rn isin the second posture, obtaining a second moving amount of thepredetermined part within the coordinate system of the medical robotsystem, the second moving amount being observed when the posture of therobot arm is changed from the first posture to the second posture, andon a basis of the first moving amount and the second moving amount,deriving correction data used for correcting an error between a movingamount of the robot arm within the coordinate system of the medicalimage diagnosis apparatus and a moving amount of the robot arm withinthe coordinate system of the medical robot system.
 14. The medical imageprocessing method according to claim 9, wherein the medical imagediagnosis apparatus comprises a couchtop, the method further comprising,when a relative positional relationship between the couchtop and themedical robot system is changed, notifying the medical robot system of achange amount in the positional relationship.
 15. The medical imageprocessing method according to claim 14, comprising, when at least oneof the following two is changed within the coordinate system of themedical image diagnosis apparatus due to either moving of the couchtopor moving of a gantry to which the robot arm is fixed: (i) a distancebetween the couchtop and the robot arm on at least one of a plurality ofaxes structuring the coordinate system of the medical image diagnosisapparatus; and (ii) a rotation angle of the robot min with respect to arotation angle of the couchtop around at least one of the plurality ofaxes, notifying the medical robot system of at least one selected frombetween a change amount in the distance between the couchtop and therobot arm and a change amount in the rotation angle of the robot armwith respect to the rotation angle of the couchtop.
 16. The medicalimage processing method according to claim 9, comprising deriving theinformation by arranging the first position and the second position tocoincide with each other, arranging the first direction and the seconddirection to coincide with each other, and arranging the first rotationangle and the second rotation to coincide with each other.